PAPR and PICR Reduction of OFDM Signals with Clipping Noise-based Tone Injection Scheme

Abstract

Orthogonal frequency-division multiplexing (OFDM) suffers from a high peak-to-average power ratio (PAPR). Tone injection (TI) extends the original constellation to several equivalent points so that these extra freedom degrees can be exploited for the PAPR reduction. However, optimal TI requires an exhaustive search over all possible constellations, which is a hard discrete optimization problem. To address this problem, a novel TI scheme that uses the clipping noise to find the optimal equivalent outer ring extended constellations (ECs) and hexagonal constellations (HCs) is proposed. By minimizing the mean rounding error of the clipping noise and possible equivalent constellations, the proposed scheme can easily determine the size and position of the optimal equivalent constellations. Second, a new TI scheme is also introduced to reduce the nonlinear distortion in the presence of a power amplifier (PA). This scheme takes the root-mean-square peak-interference-to-carrier-ratio (RMS-PICR) reduction as the target to obtain a better bit error rate (BER) performance. Simulation results show that, to achieve a considerable system performance, the proposed TI schemes only need 18 fast Fourier transforms (FFTs), whereas other TI and partial transmit sequence (PTS) schemes need hundreds of FFTs.